* update AlertingEnabled and UnifiedAlertingSettings.Enabled to be pointers
* add a pseudo migration to fix the AlertingEnabled and UnifiedAlertingSettings.Enabled if the latter is not defined
* update the default configuration file to make default value for both 'enabled' flags be undefined
Misc
* update Migrator to expose DB engine. This is needed for a ualert migration to access the database while the list of migrations is created.
* add more verbose failure when migrations do not match
Co-authored-by: gotjosh <josue@grafana.com>
Co-authored-by: Yuriy Tseretyan <yuriy.tseretyan@grafana.com>
Co-authored-by: gillesdemey <gilles.de.mey@gmail.com>
* Alerting: Validate contact point configuration during the migration
This minimises the chances of generating broken configuration as part of the migration. Originally, we wanted to generate it and not produce a hard stop in Grafana but this strategy has the chance to avoid delivering notifications for our users.
We now think it's better to hard stop the migration and let the user take care of resolving the configuration manually.